Production of clean oils at coal distillation plants



ou, 2s, 1932.

INVENTR www /EY @M M 762ML;

ATTORNEYS Filed May 3, 1929 @i .uw AV S P MILLER PRODUCTION OF CLEAN OILS AT COAL DISTILLATION PLANTS Oct. 25, 1932. s, P. MILLER 1,884,087

PRODUCTION OF CLEAN OILS AT COAL' DSTILLTION PLANTS Filed may 5, 1929 sheets-sheet 2 ATTCRNEYS Patented ct. 25, 1932 STUART' PRMELEE MELER, @E ENGLEWGD, NEW EERSEY, dSSEGlilOB TD THE BARRETT CMPANY, @F NEW YORK, N. Y., A CBPBTION 0F NEW JERSEY EJDUCTIUN F ELEM? OILS AT Cahill. DISTHILATIN PLANTS Application nica Hay 3, wist?. Serial Eto.

rllhis inventiony relates to an improved method ot operating a coal distillation plant. lt can readily he applied at gas retort plants and at by-prdouct coke plants. As described here it relates particularly to the operation of a coke oven battery. The invention includes an improved process of Voperation and improved apparatus therefor. According to this invention, coal distillalo tion gases which may result from lthe ordinary operation of a battery of coke ovens, or other coal distillation means are subjected to a cleaning treatment and the cleaned gases are passed to condensers which may be ofthe R5 ordinary type. Other coal distillation gases Which have been employed for the distillation of tar and are enriched in constituents volatilized from the tar and which are cleaned as a result of the intense scrubbing 2o to which the gases are subjected during the distillation as carried out according yto this invention, are condensed in the samecondensing system with the first-mentioned coal distillation gases which are cleaned before entering the condensers. The oils separated from the gases in the condensers are clean oils and comprise oils directly 4recovered from the gases Without distillation as Well as clean distillate. The oils may be condensed 3'0 in a single condenser to produce a total condensate or fractional condensing means may be employed to produce separate clean oil fractions;

According to the usual method of operating a5 a coke oven battery, the gases from the various ovens are collected in a gas-collector main and there artially cooled. The resulting gases are tlien passed to condensers Where they are further cooled, at each of the cool- '46 ing steps tar is separated from the gases, a

relatively heavy tar in the collector main and a tarry oil in the condensers. The various tars are ordinarily collected in one tar storage tank and the total tar thus produced is in many cases shipped to a tar distillation plant for the production of clean oil distillates and pitches, etc.

According to the present invention, the

production of clean oils may be carried out at the coke oven battery and pitches of various melting points may also be produced at the battery. This results in considerable saving due to the saving in transportation and handling and furthermore by producing clean oils according to the process disclosed a higher yield of oil and lower yield of pitch is obtained than is ossible by the methods hitherto employed or the distillation of tar and production of pitch.

'The ordinary methods of distilling tar w cause decomposition of various constituents of the tar, more particularly decomposition of the higher boiling constituents. Such decomposition results in a decrease in yield of oils and a corresponding increase in yield of 55 pitch and the pitch produced has a relatively high ree carbon content due to the production of free carbon by the decompositionof the oils. This decomposition of the oils results from overheating of the tar which may be local overheating, maintaining the tar and vapors at an elevated temperature over a prolonged period of time and other conditions inherent in the ordinary processes of distilling tar.

According to the present invention, tar in the form of an intense spray is distilled by intimate contact with hot coal distillation gases. A stream of the hot gases, for example, hot coke oven gases, is passed thru the still in which the distillation takes place and the tar is sprayed up into direct contact with the hot gases in the still. The stream of gases passing thru the still sweeps `vapors from the still almost immediately as they are formed, 95 thus preventing, atleast to large extent, the decomposition which results from the prolonged heating of such vapors. Where the tar is brought into contact With the gases by spraying the tar into the hot gases, a large surface of the tar is exposed to the gases and rapid distillation of volatile constituents :from the gases results. By maintaining an intense, constantly changing spray of tar in the vapor space of the still, and filling the vapor space of the still with the spray, and heating the tar by the hot gases which pass thru this vapor space, any overheating which may occur is of extremely short duration as the surface of tar exposed to the gases is continuously changing. The spray of tar in the gases is so line and so well distributed that due to the rapid distillation of tar in the hot gases, the gases are rapidly cooled.

Where tar is intensively sprayed into the gases entrained impurities are removed from the gases and form a portion of the pitch resulting from the distilling operation. Aecording to this invention, the spray of tar thrown into the gases in the still is so intense that substantially all .entrained matter is scrubbed from the gases. The gases which pass from the still to the condensers are clean v gases enriched in condensable oil vapors and on cooling yield clean oils. The distillation and cleaningare carried on simultaneously by producing an intense spray of tar in the gases. Where thegases are sprayed in this manner, the volatile constituents of the tar are readily released and pass off with the gases and the gases are simultaneously enriched, scrubbed and substantially deterred. The spray, according to the preferred orm of carrying out the invention as herein disclosed, is very intense and is so line and exposes such a large surface of the tar to the action of the gases that heat interchange from gas to tar is almost instantaneous. The tem! perature ofthe gases is almost instantaneously lowered below the point at which decomposition of tar or oils occurs to any considerable extent. The possibility of overdistilling the tar and producing colle is practically eliminated. Where aline spray of tar is brought into direct and intimate contact with 'the gases and the spray oi tar Within the gases is an intense spray, volatile constituents may be removed from the tar with but little decomposition thereof.

The presence of the Various non-condensable and substantially inert gas constituents making up the coke oven gases sweeping thru the still lowers the boiling temperature of volatile constituents of the tar in the still and these constituents, more particularly the higher boiling constituents, are therefore distilled at a considerably reduced temperature, as compared with temperatures normal to ordinary distillation methods, and consequently the decomposition ordinarily involved in the distillation of such constituents is avoided. By flushing the still with hot coke oven gases and removing the volatile constituents from the still as they are Jformed, decomposition of these vapors by prolonged contact with the hot gases is prevented and a higher oil yield is obtained than would other- Wise be obtainable. Simultaneously, by carrying out the distillation as a continuous process, the time during which the tar is raised to a high temperature, i. e., the time during which it is retained in the still, may be relatively short.

' In addition to the production of oils by the distillation of tar this invention provides for recovering clean oils directly from coal distillation gases. and the clean oils thus produced are recovered in the samecondenser as the clean distillate resulting from the distillation of the tar by the hot coal distillation gases. Clean oils are produced which comprise clean oil distillate resulting from the distillation of tar and clean oils produced di rectly by cooling coke oven gases or other coal distillation gaseswhich have been subjected to a cleaning operation.

The cleaning of the gases is advantageously carried out at a high temperature. In the opoperation of a coke oven battery, for example, the cleaning apparatus may advantageously be located adjacent to the ordinary collector main which may be operated at temperatures higher than normal so that the gases pass from the collector main into the cleaning apparatus at a high temperature.

An electrical precipitator, for example a precipitator of the Cottrell type, such as is employed for remov." ng suspended impurities from gases may advantageously beemployed. Such a precipitator comprises vertical tubes which serve as collecting electrodes and discharge electrodes are suspended in these vertical tubes. lThe gases to be treated pass thru the tubes, and areordinarily passed up thru the tubes. Due to the silent electrical discharge between the discharge electrode and the tubes which serve as the collecting electrodes, entrained matter carried by the gases is thrown out of the gases on to these collecting electrodes.

Where electrical precipitators are employed for cleaning the gases, according to this invention, the precipitators should be employed at a temperature at which there is no danger of coking tar or pitch constituents which may settle out upon the electrodes of the precipitator or if the precipitator is employed at a high temperature, means should be employed for preventing accumulation of tarry and pitchy constituents on the electrodes which would result in coking thereon. Such deposition and coking may be prevented by Washing the electrodes with tar which may be sprayed into the top of the tubes or may be caused to flow down the tubes in any other suitable manner to keep them clean.

The collector main of the coke oven battery f dium is brought into contact with the gases and the extent to which the gases in the collector main are cooled may advantageously be reduced, in order that the gases will leave the main at a higher temperature than usual and carry over into the condensers a higher percentage of oils than usual. In passing to the condensers, the gases pass thru an electrical precipitator in which they are cleaned. The temperature at which the cleaning of the gases takes place may be sufiiciently high to allow the gases to pass to the condensers carrying with them vapors of higher boiling oil constituents which are ordinarily separated rom the gases in the collector main. By regulating and reducing the amount of cooling to which the gases 'are subjected in the collector main, higher boiling oils of desired boiling range may be recovered directly in the condensers, and due to the cleaning of the gases these oils are recovered directly as clean oils.

Instead of employing an electrical precipitator, other means for cleaning the gases may be employed as, for example, a scrubber in which the gases are brought into contact with an intense line spray of tar or pitch which substantially de-tars the gases. The gases may be scrubbed with a pitch of substantially the same composition and temperature as that carried by the gases in which case the composition of the condensable oil constituents in the gases will not be altered to any substantial extent nor will the composition ofthe gases be altered except for the removal of entrained impurities. If a tar or tarry oil, comprising constituents which are, volatile at the temperature at which the gases pass thru the scrubber, is employed as the scrubbing medium, these lower boiling constituents may be volatilized from the scrubbing medium so that the gases passing from the scrubber and entering the condensers will be enriched to some extent by lower boiling condensable constituents, and may likewise give up to the scrubbing medium some of the higher boiling condensable oils in the gases.

rThe entrained impurities removed from the gases in the precipitator or in a scrubber employing pitch lof the same composition and temperature as that carried by the gases, or a tar or tarry oil which is distilled by the gases in the scrubber to remove lower boiling constituents, will constitute a pitch of higher or lower melting point, depending upon the temperature of the gases passing thru the cleaning device and also upon the extent to which the distillation is' carried in case of 'a scrubber employing a tar or tarry oil as the scrubbing medium. Vvlhere the gases are passed thru the cleaning device at a high temperature, a relatively high melting pitch, for example a pitch with a melting point in the neighborhood of 200" F., or 250o F., or higher, may be obtained directly from the gases.

The pitch obtained from the gases during the cleaning operation may be distilled in the still which comprises a part of this invention and in which the distillation is carried on by hot coke oven gases, direct from the ovens of the battery. The pitch may be distilled to a higher melting point pitch with a melting point e. g. of 350 or 400 F., or even higher. Instead of distilling this pitch, the still may be employed for distilling the heavy tar from the collector main. If all of the heavy tar from the collector main and the residue from the cleaning operation are distilled at the coke oven battery, according to this invention,

there will be no tar as a result of operating according to this invention, pitch and clean oils being produced instead.

Together with the tar from the collector main and precipitator, other tar may be distilled in the still or the only tar distilled within the still may be a tar from some other source than the coke oven battery itself. Tar from the coke oven battery may be distilled together with a tar of a different grade, such as water gas tar or gas retort tar, etc., to produce a blended pitch product, and to produce a blended clean oil as a result of blending the distillate thus produced with the clean oil condensed directly from the cleaned coke oven gases. I

Where the distillation in the collector main is carried to the point of producing a high meltingl point pitch, higher boiling point constituents', which may comprise resinous and greasy constituents, which are solid or semisolid at ordinary temperatures, may be carried by the gases passing from the still to the condensers. Such higher boiling constituents may advantageously be separately recovered in a separate condenser before the gases used for distillation are admitted to the condenser employed for cooling both these gases which have been utilized for distilling tar and the other gases resulting from cleaning ordinary coke oven orother coal distillation gases as contemplated by this invention.

The grade of tar distilled within the still may be varied depending upon the type of clean oil. products desired. If a tarry oil, such as the tarry oil recovered'from the condensers of a lcoke oven battery when operated in the usual manner, is distilled in the still, the clean oils obtained according to this invention, will be rich in low boiling constituents and may have a high tar acid content.

When the gases employed for distilling tar are enriched in oils of lower boiling range, a fraction which is rich 'is naphthalene may be obtained. rThis' may readily be treated for the recovery of naphthalene.

The tar acid oils produced according to this invention, are clean oils and may be directly treated with an alkaline reagent such as a solution of caustic soda to recover the tar acids therefrom.

After leaving the condensing system the gases may pass to the ordinary means for the recovery of ammonia and light oils.

The invention will be turtherdescrihed in connection with the accompanying drawings as applied to the operation of a colte oven battery, but it is intended and should he understood that the invention is not limited thereby.

Fig. 1 is a plan view of a. colse oven battery equipped tor carrying out this invention;

Fig. 2 is an elevation partly in section showing the still and hot condenser of Fig. l;

Fig. 3 is a cross-section on the line 3-3 of Fig. 2;

Fig. 4 is a cross-section on the line 4-4 of Fig. 2; and

Fig. 5 is' a detail showing means or washing the tubes of a precipitator with tar.

In the drawings 5 indicates a, colte oven battery, the ovens ot' which are connected with the three collector mains t. 7 and 8 thru uptake pipes 9. The gases pass from the ovens thru the uptake pipes and collector mains to the cross-over mains l0, l1 and 12. This apparatus may be oi the usual type er;- cept that in the crossover mains electrical precipitators 13, 14 and 15 are located .for cleaning the gases leaving the collector mains. The precipitators are advantageously located adjacent to the collector mains so that the gases pass from the collector mains lnto and thru the precipitators at an elevated temperature substantially that at which they leave the mains. The mains 10, il and l2 and the precipitators may 'advantageously be well 1nsulated.

From the precipitators the gases pass into the main 16 and thence to the coolers 17 and 18, which may be direct or indirect coolers. They are here shown as direct coolers o f the type usually employed in connection with a Schiet-Solvay plant. From the coolers the gases pass thru an exhauster 1l) to means for the recovery of ammonia and light oils. The apparatus thus far described may be of the usual type, e. g. the usual Seniat-.Solvay or Koppers type, except that a precipitator 1s located in each of the cross-over mains.

At the rear of the oven is a still 25. This still is employed for the distillation of tar and the tar is distilled by being brought into direct and intimate contact with hot coke oven gases which pass thru the still. The gases used for the distillation pass up thru uptake pipes 26 into the hot gas header 27 and thence into the still 25. By the proper manipulation of valves located in the uptake pipes 26 and valves-of the usual type in the uptake pipes 9 connecting the saine ovens to the collector main 8, the gases from these ovens may be passed either into the collector main 8 or into the hot gas header 27. The gases collected in the header are employed for distilling tar. They enter the still at 28 and leave the still thru the tower 29 and pass thru the opening 30 into the main 3l.

The tar which is distilled in the still 25 may be heavy tar trom the tanks 32 which collect the heavy tar from the collector mains which is drawn oli" thru the decanters 33. Heavy tar or pitch separated troni the gases in the precipitators and drawn otl into the tanks 34 may be distilled in the still 25. Tar from either of these sources may be pumped thru the line 35 to the still. or tar from some other source such as 36 may be pumped to the still.

The tar enters the still thru the nozzle 37 in the tower 29. Above and below the nozzle baling means 38 and 89, which may advantageously be Raschig rings, are used to advantage. The tower serves as a chamber in which entrained particles ot spray carried over by the gases from the still may settle out of the gases and also as a place in which the tar going to the still may be preheated and partially distilled. The bale 38 located below the nozzle serves to bring the tar sprayed into the tower thru the nozzle and the gases passing up thru the tower into intimate contact and also to remove entrained impurities from the gases and to heat the tar. The baille 39 above the nozzle tends to prevent entrainment of f spray from the nozzle in the gases leaving the tower.

The residue of preheated and partially distilled tar or pitch which collects in the bottom of the tower 29 is advantageously withdrawn thru the line 40 and admitted to the still at 41. Where preferred, the tar may be admitted to the still thru the line 42 without first passing thru the tower; the tar may be preheated or not as desired.

Within the still means is provided for spraying the tar which collects in the still up into the gases. For this purpose a cylinder 43 is shown which is advantageously positioned in the still close to one of the sides of the still and is so situated that it dips to a slight extent into the body of tar or partially distilled tar maintained within the still. This cylinder 43 is connected with the motor 44 and is rapidly rotated by this motor at a speed, for example in the neighborhood of 900-1200 R. P. M. The rotation of the cylinder causesthe tar to be intensively sprayed up into the gases and by proper regulation ot the speed of rotation of the cylinder and the extent to which it dips into the tar. a line spray of tar in the gases may be produced which will substantially de-tar the gases so that on cooling the gases leaving the still or tower substantially clean oils will be obtained.

The pitch resulting romthe distillation of the tar is withdrawn thru the trap 45 .by means of the levelling arm 46. By proper adjustment of this levelling arm the level of the tar or partially distilled tar within the still may be maintained at the proper height. Where a relatively high melting point pitch is produced, such as a pitch with a melting point of 200 F. or even of 400 F., the tar may advantageously be chilled as it is withdrawn from the still. F or this purpose, the tar is sprayed with water from the line 48 in the trough 49 and the granulated pitch which results is collected in the bin 50. The pitch may be separated from the water inany suitable way.

lhere the distillation of the tar within the still is carried to a point where a high melting point pitch is produced and high boiling and resinous constitutents are volatiliZed from the tar, the gases and vapors leaving the still may if desired be cooled in regulated manner to remove such higher boiling constituents before these gases enter the condensers 17 and 18. For this purpose a hot condenser 51, also commonly known as a partial condenser, is provided although it is to be understood that the gases leaving the still may be passed directly to the condensers without partial cooling as herein contemplated. Where tarry oils are'distilled within the still or where only lighter oils are volatilized within the still, such partial cooling of the gases may ordinarily be eliminated. The condensate from the hot condenser is collected in 52.

rlfhe elements of the apparatus thru which the hot gases employed for distillation pass are advantageously well insulated to prevent undesirable cooling of the gases thru heat radiation. Such insulation is shown around the uptake pipes 26, the hot gas header 27, the still 25, the tower 29 and the main 53 leading from the tower to the hot condenser 51 in Fig. 2. The gases leaving the hot condenser which are clean gases and which contain vapors of lower boiling constituents, pass thru the main 54 into the coolers 17, 18. The main 54 and also the main 16 may advantageously drain toward the condensers. In the condensers 17, 18 the enriched gases from the still 25 are blended with the clean gases from the cross-over main 16. The gases may be cooled with ammonia liquor orwater or they may be cooled indirectly and the condensate and ammonia liquor resulting from such cooling are advantageously drawn oii' into one or more decanters in which the ammonia liquor and clean oils are separated. The gases are advantageously fractionally cooled, so two decanters 55 and 56 and two clean oil containers 57 and 58 are shown. One total condensate may be produced from these gases where desired, or the gases may he fractionally cooled in indirect condensers or refluxing towers, as desired.

lVhere tarry oils containing relatively low boiling constituents are distilledwithin the still 25, or where a tar rich in lower boiling constituents is distilled within this still and the distillation is not carried to the extent required to produce a high melting point pitch, a clean total oil of relatively low boiling range may be produced. The oil will be a clean product, substantially free from pitch and tar, since the oils are clean oils.

Where several oil fractions are desired, the gases may be cooled stepwise in several coolers and the resulting oils may be kept separate. Where closer boiling fractions are desired or fractions enriched in some particular component or group of components are required, the enriched gases may be passed up thru a rectifying tower down which oil of the character required for the desired degree of fractionation is flowing. As is well known to those skilled in the art, a number of factors, such as type of reflux oil, temperature of oil, quantity of oil, velocity of the 'gases thru the tower, etc., require regulation within reasonable limits to produce oil fractions of desired character. Where several oil fractions are desired, several fraotionating towers with separate oil collecting means may he employed.

Where an oil of relatively high boiling range is to be produced in a fractionating tower, the .gases from the collector mains 6, 7 and 8 are advantageously cleaned at a high temperature. Where the temperature is sufficiently high to prevent the deposition of a sufiicient quantity of lower boiling compounds on the collecting electrodes of the precipitators employed for cleaning the gases in order to keep these electrodes washed clean, the electrodes may advantageously be washed with tar supplied to the precipitator for this purpose.

Fig. 5 shows a detail of a part ofthe precipitator 13 equipped with means for washing the collecting electrodes with tar. The precipitator comprises tubular collecting electrodes 80 supported in an upper header 81 and a lower header (not shown). The gases to be treated may pass up thru these tubes. They are subjected in their passage thru the tubular electrodes to an electrical discharge at high potential passing between the discharge electrodes 82 and the tubes 80. The electrodes 82 are suspended from the busbar 83 which is supported by the insulators 84 in the chamber 85. The gases pass from the precipitator at 86.

The tubes 80 may be continuously washed with tar admitted thru the pipe 87. This tar collects on the header 81. The tops of thetubes .are advantageously serrated to provide even distribution of the tar to the tubes. The tar passes down the tubes and due to its solvent action prevents the formation of deposits on the walls of the collecting electrodes 80. The tar may be distilled to some extent in passing down thru the tubes in contact with the hot gases; The undistilled residue of the tar together with material thrown out of the gases in the precipitator is drawn olf 10 each of the collector mains may be de-tarred by apparatus of this type instead of the precipitator shown; on subsequent cooling clean oils will be produced. Such de-tarring or scrubbing means may be employed in the place of theelectrical precipitators 13, 14, and

15, according to this invention.

In employing such a device for scrubbing the gases, the gases from the collector main advantageously enter the scrubber at the 2,point corresponding to 28 in the still 25 of Fig. 2 and pass thru the outlet 30 to the condensers thru the main 16. Where the gases are sprayed with a tar or pitch of the same composition and temperature as that carried by the gases, the operation is simple when carried out in apparatus of this type. Tar or pitch is added to the scrubber at the beginning of the process and the agitating member is set in motion. As the gases are scrubbed the tar or pitch which is removed from the gases is sprayed back into the gases to remove further entrained impurities. There is no need for adding any scrubbing medium to the scrubber. The excess pitch removed from the gases is drawn oif as a product of the process. Where desired this product may be distilled .within the still 25. The tower of the scrubber corresponding to the tower 29 of the still need not contain any nozzles and one set of bailies, or no bailies at all may produce satisfactory results.

Where a tar such as a tarry oil which is of different composition from the entrained impurities carried in the gases is employed for cleaning the gases, such tar may advantageously be sprayed into the gases in the tower and pass down thru the tower and thence into the body of the scrubber thru the passage corresponding to the passage 59 of the still 25 which connects the still with the tower, or

thru aline corresponding to the line 40 into the scrubber itself. The How of the scrubbing medium thru the scrubber may be in a general concurrent or counter-current direction.

In the still employed for distilling tar, as in the still 25, the fiow of tar-and gases is advantageously concurrent, at least as far as 'the final stages of the distillation are conried out in plants comprising one collector main or more, together with a still which employs hot coal distillation gases for the distillation.

Although the invention has been described more particularlyas applied tothe operation of a coke oven battery, it is not to be considered as limited thereto but is also applicable to other coal distillation plants, e. g., gas retort plants.

The invention may be readily adapted to existing plants without any substantial alteration except for the addition of means for cleaning the gases and the provision of a suitable still.

I claim 1. The method of treating the distillation gases resulting from the distillation of coal at a coal distillation plant which comprises cleaning a portion of the coal distillation gases at a high temperature to remove entrained impurities, distilling tar by bringing it in the form of a fine intense spray into direct contact with another portion of the coal distillation gases while still at a high temperature whereby these gases are cleaned and then combining the resultin clean enriched gases with the first mentione clean gases and condensing them to produce clean oils.

2. The method of treating the distillation gases resulting from the distillation of coal at a coal distillation plant, which comprises cleaning the gases from certain ovens or retorts at a high temperature, bringing tar in the form of a fine intense spray into intimate contact with gases from other ovens or retorts while the gases are at a high temperature whereby the tar is distilled and the gases are detarred, and then combining and cooling the resultinenriched gases with the first mentioned c ean gases to produce clean oils.

3. The method of treating the distillation gases resulting from the distlllation of coal at a coke oven plant, which comprises collecting the gases from certain ovens in gas collector mains, passing the gases from these mains thru cleaning apparatus at a high temperature and cleaning them therein, bringing the gases from other ovens into contact with tar in the form of a fine intense spray thereby distilling the tar and simultaneously cleaning the gases, combining the resulting clean enriched gases with the first-mentioned clean gases and cooling them to condense clean oils therefrom. l

4. The method of treating the distillation gases resulting from the distillation of coal at a coke oven battery which com rises co1- lecting the gases from a portion o the ovens into one or more collector mains, regulating the cooling ofthe gases in the collector mains so that the gases leave the mains at a high temperature, cleaning the gases by passing the gases from each main thru an electrical precipitator and subjecting them to an electrical discharge therein, employing gases Y from other ovens for distillation bybringing the gases are cleaned, combining the resulting clean enriched gases with the first-named clelesan gases and cooling them to produce clean o1 5. The method of treating the distillation gases resulting from the distillation of coal at a coke oven battery which comprises` collecting the gases from a portion of the ovens into one or more collector mains, regulating the cooling ofthe gases in the collector mains so that the gases leaving the mains are still at high temperature, scrubbing the resulting gases by bringing them into intense and intimate contact with pitch of substantially the same composition and temperature as that carried bythe gases whereby the gases are substantially detarred, bringing gases from other ovens into intimate contact with a tine spray of tar whereby the tar is distilled and the gases are detarred, combining the resulting gases with the first-mentioned detarred gases and cooling them to separate clean oils therefrom.

6. The method of treating the distillation gases resultin from the distillation of coal at a coke ovenattery which comprises cleaning the gases from a portion of the ovens at a high temperature, bringing the gases from other ovens into intimate contact with a fine intense spray of a heavy tar whereby the tar is distilled and the gases are detarred, subjecting the resulting clean gases to partial cooling and condensing a part of the oil vapor therefrom, then combining the resulting partially cooled gases with -the gases resulting from the first-mentioned cleaning operation and cooling the combined gases to separate clean oils therefrom.

7. The method of treating the distillation gases resulting from the distillation of coal at a coke oven plant which comprises collecting the gases from a portion of the ovens in one or more collector mains, partially cooling them therein to separate a heavy tar therefrom, cleaning the resulting gases and collecting the impurities removed from the gases, mixing the heavy tar and the collected impurities, l,bringing the mixture in the form of an intense spray into intimate contact with hot gases from other ovens whereby the tar percentage of low'boiling oils in the form of a fine intense spray, thereby distilling low boiling oils from the t-ar and detarring the gases with the tar being distilled, combining the resulting gases with the first-mentioned 70 gases after cleaning and cooling them to condense oils therefrom.

In testimony whereof I alix my signature.

STUART PARMELEE MILLER.

and impurities are distilled and the gases are detarred', combining the clean gases er1-'- riched in this distillation process with the gases from fthe first-mentioned cleaning operation and cooling them to produce clean oils.

8. The Irijethod of treating the distillation gases resulting froml the distillation of coal at a coke oven battery which comprises cleanlng a portion of the gases from the battery, brlnging another portion of the gases into intimate contact with tar containing a high 

